Many applications require the orthogonal, electrical connection of one printed circuit board to other thin circuit boards or aperture sheets suitable for microwave frequencies. Although a number of techniques have been employed in the past for connecting boards together, space considerations, cost and other factors present problems with their use. For example, one common type of connection for mounting two boards perpendicularly to one another involves the use of pin arrays and sockets. One of the boards carries a number of spaced pins and the second board mounts a socket which receives the pins when the two boards are connected together. SMT radio frequency connectors systems are generally similar in construction. Both of these connector systems are relatively large and expensive, and cannot be readily made to the tolerance requirements of many applications.
Flexible or “flex” circuits provide another option of mounting boards perpendicular to one another. Flex circuits are used in a wide variety of applications where an electrical circuit must bend around corners or be flexed during operation. In order to mount two boards perpendicularly to one another, a hard bend must be made in the flex circuit which is subject to fatigue at certain temperature cycles. Flex circuit are also difficult to assemble in many instances, especially in applications with very limited spacing between boards or other components.